Sound-reproducing machine



H. 1. uRBoRow AND B. L. wlNnERS.

SOUND REPRODUCING MACHINE.

APPLICATION FILED MAH.18,1920.

Patented Mar. 8, 1921.

UNITED sTATEs PATENT OFFICE.

HARRY J. DURBOROW AND BAYARD L. WINDERS, OF PHILADELPHIA, LPENNSYLVANIA.

SOUND-REPRODUCING MACHINE.

Specication of Letters Patent.

Patented Mar. 8, 1921.

Application led March 18, 1920. Serial No. 366,817.A

To all whom it may concern.'

Be it known that we, HARRY J DURoRow and BAYARD L. WINDERs, citizens of the United States, residing at Philadelphia, county of hiladelphia, and State of Pennsylvania, have invented certain new and useful Improvements in Sound-Reproducing Machines, of which the following is a speciication.

The main object of our invention is to improve the quality of tones reproduced by talking machines.

It is well known that a mica diaphragm of the type usually employed on talking machines is decidedly limited in its capability to reproduce sounds which are capable of being recorded in a record. For example an extremely strong or high tone of a Voice or musical instrument causes a blasting sensation when reproduced by a mica diaphragm. Further than this if the vibrations imparted to a mica diaphragm become too great they will not be individually reproduced and the sensation upon the ear is that of a conglomeration or confusion of sounds.

Another object of our invention is to provide .a diaphragm which is so constructed and which has such characteristics that loud or overtones will be reproduced clearly and accurately without blasting or association with foreign tones.

A further object of our invention is to eliminate or greatly reduce the surface noise usuall resent on talking machines due to the frictlonal engagement of the needle with the record.

These objects, and other advantageous ends which will be described hereinafter, we attain in the following manner, reference being had to the accompanying drawin s in which igure 1 shows a sound box including a diaphragm made in accordance with our invention,

Fig. 2 is a sectional elevation, partiy broken away, showing 'the cork diaphragm of Fig. 1 drawn on an enlarged scale and prior Vto treating or processing the same in accordance with our invention,

Fig. 3 is a view of similar character to Fig. 2 showing the diaphragm of Fig. 2 having received one step of a processing' operation which forms a part of our invention,

Fig. 4 is a fragmentary section drawn of a greatly .increased scale illustrating the characteristics of a portion of the diaphragm after said first step of the processing operation,

Fig. 5 is a view of similar character to Fig. 3 showing the diaphragm as it appears after the second step in the processing there- `annular recess 13 provides a shoulder 14 and a circular inner edge 15 preferably concentric to the axis of the sleeve 11. A rubber ring or gasket 16 is positioned within the recess 13 abutting the shoulder 14 and circular edge 15.

A cork diaphragm 17, which is processed according to our invention hereinafter described, is placed so that the surface on one side adjacent the peripheral edge 18 abuts the rubber gasket 16. A second rubber gasket 19 abuts the opposite surface of the iaphragm 17 adjacent its peripheral edge 17 and a portion of 'this gasket 19 projects slightly out of the recess 13 into a circular cavity 20' of greater diameter than the recess 13. A ring 21 fits within the cavity 20 and abuts the outer surface of the' gasket 19. The innermost portion of the cavity 20 provides a shoulder 22 which is located inwardly from the outer part of the gasket 19 so that normally there is a space between the ring 21 and the shoulder 22. The ring 21 is secured by means of screws 23 to the part 24 of the sound box so that by tightening on the screws 23,A the gaskets 16 and 19 will be compressed and the diaphragm 17 will be held therebetween. In View of the space normally existent between the shoulder 22-and ring 21, if the gaskets 16 and 19 should become flattened or lose a ortion of their resiliency after a time, it is possible to tighten up on the screws 23 and thereby P: Uv

take up for any looseness present between the gaskets and the diaphragm.

The shape, proportion, and the treatment or processing of the cork diaphragm forms a very important feature of our present invention and will now be described.

Our improved diaphragm 17 includes a body portion which is made from a piece of cork of good quality. This body portion is shaped as shown in Fig. 2 by forming a flat surface 26 by grinding or cutting the same in a plane at right angles to the axis thereof. The opposite surface 27 is curved convex to the flat surface 26 so that the body portion is thickest at its axis and becomes gradually thinner toward the peripheral edge 18. After the body portion 25 has been made in the shape as above described, we coat the flat surface 2G thereof with lacquer which includes a solvent or liquid which is free liowing and readily volatile so as to cause the body portion of the lacquer to quickly How into and fill any cracks, recesses or interstices of the body of the cork adjacent the surface 2G and so that when the lacquer has dried it will fill said cracks, recesses or interstices as shown at 28 in Fig.

4 and also form a covering 29 adhering to he flat surface 26. The lacquer' is then permitted to'dry or set after which a second coating is applied directly to the covering 29 as shown in Fig. 5. This second coating is preferably made sufficiently thin to prevent it from softening the entire thickness of the covering 29 but the outer portion of the coating 29 is softened sufficiently to provide an adhesion with the material of the coating 3G. After the covering or coating 30 has been permitted to dry or set, another coating 31 of lacquer is preferably applied to the outer surface of the coating 30 and the entire structure is then permitted to dry or set.

A hole 32 is then cut axially through the diaphragm, thus recessed, and a stylus or tone bar 33 is connected to the outer surface of the coating 31 and a screw 34 is placed within the hole 32 and has a screw threaded portion 35 which engages a screw threaded hole 36 in the tone bar 33. The screw 34 has an enlarged head 87 which fits within a recess 38 cut into the convex surface 27 of the body portion 25 and in this manner the stylus bar is held directly to the outer surface of the coating as is clearly shown in Fig. 7.

ly making a diaphragm as above described the portion thereof adjacent the flat surface 2G will be rendered more dense than the part of the body portion adjacent the convex surface 27. Furthermore, in view of the application of the lacquer' or similar inaterial, as above described, a structure is provided which vis of different densities at places between opposite the greatest denn sity being at or in close proximity to the plane of the surface 26 and in view of the penetration of the lacquer or similar material as shown at 28 this density becomes less in parts approaching toward the convex surface 27. The lacquer does not penetrate through the entire thickness of the body portion 25 but on the contrary the part of the body portion 25 directly adjacent the surface 27 remains unprocessed and of the same constituency as the original cork from which the diaphragm is made.

lVe have found by actual use of a diaphragm constructed as above described that when vibrated, due to the action of the tone bar, it returns to its normal position quicker than other diaphragms in common use without stopping or cutting the tone waves short. Furthermore, when vibrating, it does not get beyond control or offer counter resistance to the vibration of the tone bar. In view of this latter characteristic our improved diaphragm prevents what is known as blasting. The vibrations of the tone bar are imparted directly to the part of the diaphragm which is of greatest density. These vibrations are taken up by the less dense part of the diaphragm and the transmission of the vibrations transversely through the disphragm causes them to pass through parts of less density until they pass through the unprocessed part of the diaphragm adjacent the surface 27 and it has been found by actual use that the features mentioned in the foregoinu objects are carried out and an accurate reproduction of sounds is attained and that the surface noise of the reproducing needle of a record is practically m'Z.

Ve are aware that cork has been previously used as material in the construction of diaphragms but we are not aware of any instance where a diaphragm has been made in accordance with l that illustrated in the drawings and above described.

While we have described our invention as taking a particular form, it will be understood that the various parts of our invention may be changed without departing from the spirit thereof, and hence we do not limit ourselves to the precise construction set forth, but consider that we are at liberty tol make such changes and alterations vas fairly come within the scope of the appended claims.

Having thus described our invention. what we claim as new and desire to secure by Letters Patent is i. A diaphragm of the character described including a body portion of cork and a coating of material adhering directly to the outer surface of said eorlr and of greater density than said body portion of the cork; and a tone bar connected t said body portion .and directly en said coating portion adjacent said flat surface; and a tone bar connected to said coating andv adapted to transmit vibrations to said coat whereby the tone bar is adapted to transmit vibrations to said coating; substantially as described.

2. A diaphragm of the character described including a body portion of cork and a coating of materlal applied on the outer surface 0f said cork and of greater density than said bodyA portion; and a tone bar having a portion clamped in direct contact with said coating, said coating bein in adhesive connection With the outer sur ace of said body portion and having integral parts penetrating into crevices, interstices or the like which lead from said surface inwardly into said body portion; substantially as described.

3. A diaphragm of the character described including a cork body portion hav in a flat surface and a surface convex to said fiat surface; a coating of material in adhesive connection with said flat surface and Vhaving illtegral.4 parts penetratin into crevices, interstices or the like of sai body ing; substantially as described.

4. A diaphragm of the character de- Amit Vibrations directly to said coating;

substantially as described.

45. A 'diaphragm of the character described including a body portion of cork and a coating of ilacquer adhering directly to one surface of said cork body portion; and a tone bar held in direct contact with said coating at a position inwardly from the outer edge of said body portion whereby the tone bar is adapted to transmit vibrations to,l

said coating; substantially as described.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

Witnesses:

ANNA REN'roN, Crus. E. Porre. 

